Direct Digital Shear Machine - GG-HM-382F

The Digital Pneumatic Shear Machine is a self-contained unit for evaluating direct and residual shear strength of soil specimens. This model features Karol-Warner's highly accurate CONBEL® pneumatic loading system to apply vertical confining pressures to specimens.

The test is performed on a variety of soil types with either undisturbed or remoulded samples. Specimens are carefully trimmed into a Direct Shear Box, which is split to allow individual movement of the upper and lower halves. A vertical confining load is applied to the specimen, and a horizontal shear force is applied to the lower half of the shear box while the upper half remains stationary. After shear failure has been measured, the force direction is reversed to determine residual shear values.

Models have a load cell with digital readout for shear load measurement, and horizontal and vertical displacement transducers to measure consolidation and shear displacement. Total shear capacity is 6.67kN.

Confining loads are controlled through a precision regulator with included calibration chart, and the digitally displayed settings are accurate to ±0.25%. A stepper motor drive controls horizontal strain rates to ±1% from 0.0001- 0.0025—7.62mm/ min, and is easily set with digital thumbwheels. HMA-735, 63.5mm diameter stainless steel shear ring, porous stones, drainage plates and a water chamber constructed of Teflon coated, anodized aluminium for corrosion resistance are included. Unit requires 90psi (6.2bar) user-supplied compressed air source.


·         Self-contained unit eliminates the need for weights when applying vertical confining pressures

·         Load cell with digital readout provides shear load measurement

·         Horizontal and vertical displacement transducers measure consolidation and shear displacement

·         Total shear capacity of 6.67kN

·         Settings accurate to ±0.25%

·         Stepper motor drive controls strain rates to ±1% 0.0025—7.62mm/ min


Included Items:

·         HM-382 Digital Pneumatic Shear Machine

·         HMA-735 63.5mm x 25.4mm Round Shear Ring & Box

·         Porous Stone

·         Drainage Plate

·         Water Chamber


Optional Accessories:

·         RS-232 to USB Adapter Cable transfers data to user’s PC in ASCII format

·         Geotechnical Data Acquisition Suite (GEO-DAS) collects and analyses soil testing data

·         Rolling Cart for Load Frame Testing Equipment positions load frames at the proper working height

·         Shear Rings & Boxes for Direct/Residual Shear Machines enable opposing shear forces to be applied to soil specimens

·         Cutters for Direct/Residual Shear Machines are used to trim samples to the proper size

·         Extruders for Direct/Residual Shear Machines offer easy control when working with samples 

Digital Direct Shear Machine - 305mm - G-385F


The 305MM Square Direct Shear was specifically designed for testing large soil sample sizes with soil and geosynthetics for testing coefficient of friction. Several methods of testing can be accomplished - soil to soil, soil to geosynthetic, geosynthetic to geosynthetic and GCL to GCL (geosynthetic clay liner).  The device utilises the "CONBEL” concept for consolidation loading of the sample. Sample loads are obtained by one of two pneumatic pistons. This concept increases the accuracy and sensitivity of light load settings. A small diameter rolling diaphragm piston is capable of applying light loads to 454 kg and larger piston applies loads up to 45 kn or 90kN depending on the unit selected.

Castors on the machine and compaction table make for easy movement in the lab. The machine height is a factor in the design to give the operator a convenient level for setting up and operating the machine. This includes the Compaction table that makes the sample easy to prepare in the shear rings. The rings are easily handled both installing and removing from the water chamber and the compaction table.

SOFTWARE is provided with the machine to input test data to computer (not provided) and export to Microsoft "Excel” for graphing and presenting test results.


Applying the vertical load is accomplished by setting the precision regulator to the required pressure per the pressure to load calibration chart. Load settings are verified on a pressure readout that reads to two decimal places and is accurate to 0.25%. Constant rate of displacement for the horizontal shear rate is set using the digital thumb wheels on the control panel. Limit switches are used for the home position and also to limit the travel to 102 mm. Adjustment to the limit switches can be accomplished under the control cabinet.


Consolidation and shear displacement are measured by linear displacement transducers and displayed on the digital readout along with shear load from the load cell attached to the water chamber. Data output to the computer is via an RS232 Serial Port in ASCII format. This can be exported to spreadsheet programs like "Excel”. Viewing of displays are not dependent on a computer hookup. Readout is capable of showing peak shear load.


Removing the shear rings from the water chamber in the machine is handled easily. The shear rings are pulled onto the two compaction table rollers that allow the assembly to slide easily into and out of the water chamber. Preparation and compaction of the sample or geotextile can be accomplished on the table. The table is then rolled back into position for sliding the shear boxes into the water chamber. When removing the shear boxes, it is advised to lock the brakes on the castors.


The direct shear is designed for harsh lab environments. All steel parts are powder coated and aluminum parts are hard coat anodized for corrosion resistance. Some parts are made from stainless steel.


Specimen Weight 381kg
Dimensions W 1090mm x L 584mm x H1020mm
Estimated Shipping Weight 465kg

For complete spec sheet, please contact CMT Equipment